Updated TIFF decode error message string

[HarmvandenBrand]

OSError caused by decode error should use string argument to be in line with rest of module

Changes proposed in this pull request:

• Changed an OSError raised in TiffImagePlugin.py during a decoder error to contain a str message as its argument, instead of directly passing the error code as an integer. This change brings this specific OSError in line with the way errors are raised in the rest of TiffImagePlugin.py and thus reduces surprise.

[radarhere]

Nitpick suggestion: maybe remove the colon, to more closely match

Pillow/src/PIL/TiffImagePlugin.py

Lines 1972 to 1974 in 48712f2

	if errcode < 0:
	msg = f"encoder error {errcode} when writing image file"
	raise OSError(msg)

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